1. Field of the Invention
The present invention relates to an encoded digital audio reproducing apparatus for performing reproduction and fast-forwarding/rewinding reproduction or the like in the middle of an encoded audio file.
2. Related Art
In the case of an MP4 file which is one of the formats of an encoded audio file, frame size information on each individual frame configuring encoded audio data is stored in a place (a sample size box of a header portion) different from the encoded audio data itself.
In the case where a read error or the like occurs in such an encoded audio file due to a flaw on a recording medium or the like while reading the encoded audio data, or in the case where fast-forwarding/rewinding reproduction is performed, the encoded audio data is reproduced in the middle. Concretely, whenever reproduction due to an error is performed or in fast-forwarding/rewinding reproduction, next reproduction position is to be calculated, reproduction is performed by reading the frame size information from the recording medium, calculating a frame position for starting the reproduction and reading the encoded audio data from that position.
In the case where the encoded audio file is recorded on a recording medium of a low reading speed (such as a CD), however, it is not desirable to read the frame size information each time the encoded audio data is reproduced in the middle from the viewpoint of processing efficiency.
Therefore, under normal circumstances, a frame position information table having the frame position information on each frame contained in the encoded audio data is generated and stored, based on the frame size information at a time of initial reproduction so as to realize the reproduction of the encoded audio data in the middle at high speed.
However, the number of frames of the encoded audio data is proportional to a sample rate and a tune length so that there are a number of frames in the case of a long-time tune of a high sample rate. Therefore, a large memory area must be secured in order to hold the frame size information on each frame.